As a soil release agent (also referred to as “SR agent”) which makes easier to remove a soil adhered to an treated article, known are copolymers of a polymerizable monomer containing a polyfluoroalkyl group (hereinafter abbreviated as “Rf group”) and a hydrophilic group-containing polymerizable monomer (cf. JP-A-59-204980 and JP-A-62-7782).
In order to obtain these polymers, a large amount of an organic solvent is necessary for the polymerization for the purpose of compatibilizing the Rf group-containing polymerizable monomer with the hydrophilic group-containing polymerizable monomer to give a homogeneous polymer.
In addition, usually, the carbon number of the Rf group in the Rf group-containing polymerizable monomer is substantially at least 8 (JP-A-53-134786 and JP-A-2000-290640).
The reason therefor is that the crystallinity of the Rf group is too low so that the oil repellency is vanished in air and the oily soil unremovably penetrates into the treated article, although the crystallinity of the Rf group is decreased by reducing the number of the Rf group and polymer mobility is increased for the purpose of obtaining sufficient a flip-flop property and exhibiting the soil releasability. The flip-flop property is the property that a surface molecular structure is changed depending on environments in air and in water, which is proposed by Sherman et al. [P. Sherman, S. Smith, B. Johannessen, Textile Research Journal, 39, 499 (1969)].
When, however, the number of the Rf group is at least 8, there is a trend that a large amount of the organic solvent is necessary in the course of obtaining the homogeneous copolymer and the handling of the treated article is decreased.
Further, recently, with respect to a compound containing the Rf group having 8 carbon atoms obtained by telomerization,
Federal Register (FR Vol. 68, No. 73/Apr. 16, 2003 [FRL-2303-8]) (http://www.epa.gov/opptintr/pfoa/pfoafr.pdf);
EPA Environmental News FOR RELEASE: MONDAY Apr. 14, 2003 EPA INTENSIFIES SCIENTIFIC INVESTIGATION OF A CHEMICAL PROCESSING AID (http://www.epa.gov/opptintr/pfoa/pfoaprs.pdf); and
EPA OPPT FACT SHEET Apr. 14, 2003 (http://www.epa.gov/opptintr/pfoa/pfoafacts.pdf)
have announced that a “telomer” may possibly metabolize or decompose to perfluorooctanoic acid (hereinafter referred to as “PFOA”).
EPA (Environmental Protection Agency of USA) has announced that the EPA intensifies the scientific investigation on PFOA (cf. EPA Report “PRELIMINARY RISK ASSESSMENT OF THE DEVELOPMENTAL TOXICITY ASSOCIATED WITH EXPOSURE TO PERFLUOROOCTANOIC ACID AND ITS SALTS” (http://www.epa.gov/opptintr/pfoa/pfoara.pdf)).